This project investigates the development of bimodal bilingualism by studying sign language and spoken language in young deaf children with a cochlear implant (CI) and young hearing children in deaf families (codas). Most research conducted with deaf children with CIs has focused on their development of spoken language, whether they are in oral-only or total communication programs. However, none has examined the development of sign language and spoken language as two systems of a child bilingual, comparing them with the natural bilingual situation of codas. This study also breaks new ground by comparing the development of bimodal bilingualism in two language pairs: English and American Sign Language (ASL), and Brazilian Portuguese (BP) and Brazilian Sign Language (LSB). By including two pairs in the study the research aims for a greater degree of generalizability and a better understanding of the effects of particular languages on the process of development. The research uses both longitudinal spontaneous production data and experimental tasks with children between the ages of 1 year, 6 months and 7 years to address the following three major questions: Question 1: How does early exposure to Sign Language and spoken language affect development in each modality in signing deaf children with a CI? Question 2: Is the language development of bimodal bilinguals with fully accessible input constrained in ways similar to that of unimodal bilinguals? Question 3: To what extent does the linguistic development of deaf children with CIs who receive early bimodal input resemble that of hearing bimodal bilinguals (codas)? PUBLIC HEALTH RELEVANCE: This project asks whether deaf children who have a cochlear implant can become bilingual in both spoken language and sign language in the same way that hearing children can become bilingual in speech and sign if their families use both languages. It is crucial for parents and educators to know about the ways in which this kind of bilingual situation can progress so that they can make informed choices.